Low-Level Laser Therapy for Depression

Introduction: Depression is a mood disorder that causes a persistent feeling of sadness and loss of interest.

Background: Photo biomodulation (PBM) is a new therapeutic intervention using laser-generated low-powered light therapy that has shown early promise in alleviating fatigue, depression, and pain in chronic illness. Photo biomodulation (PBM) with red and near-infrared light (NIR) -also known as Low-Level Light Therapy-is a low risk, inexpensive treatment-based on non-retinal exposure-under study for several neuropsychiatric conditions. The aim of this paper is to discuss the proposed mechanism of action and to perform a systematic review of pre-clinical and clinical studies on PBM for major depressive disorder (MDD). 

Method: A search on MEDLINE and EMBASE databases was performed in July 2017. No time or language restrictions were used. Studies with a primary focus on MDD and presenting original data were included (n=17). References on the mechanisms of action of PBM also included review articles and studies not focused on MDD.  Feasibility will be assessed by attendance, recruitment rates, and participants' views of PBM. Mixed­ effects linear regression modelling will be used to assess the PBM effect on continuous outcomes (fatigue, depression, anxiety and stress scores, and inflammation levels).

Results: Red and NIR light penetrate the skull and modulate brain cortex; an indirect effect of red and NIR light, when delivered non-transracially, is also postulated. The main proposed mechanism for PBM is the enhancement of mitochondrial metabolism after absorption of NIR energy by the cytochrome c oxidase; however, actions on other pathways relevant to MDD are also reported.

Conclusions: Studies on models indicate a benefit from PBM that is comparable to antidepressant medications. Clinical studies also indicate a significant antidepressant effect and good tolerability.